Abstract

BACKGROUND: Stereotactic Radiosurgery (SRS) is a highly conformal technique allowing a high dose of radiation to be delivered to a target lesion but the rapid fall-off in dose spares surrounding tissues. This results in a high degree of local control with low risk of side effects. In selected patients with oligometastatic disease, SRS can be a good alternative to Whole Brain Radiotherapy (WBRT) for palliation. Our centre’s policy for oligometastatic disease is to offer patients SRS (or post-operative SRS) for local control as an alternative to WBRT; no patients routinely receive this as adjuvant after SRS. AIM: To review 2 year outcomes of the SRS service for oligometastatic disease at BWoSCC and compare with local outcomes for WBRT to ensure selection criteria are robust and appropriate patients are being treated with SRS. METHODS: Electronic records were retrospectively reviewed for all patients who had SRS for 1–3 cerebral metastases from August 2012 to July 2014. Local data for WBRT has been previously accrued in similar fashion for the whole of 2012. RESULTS: With SRS, a total of 68 lesions were treated in 50 patients; 34 patients had a solitary metastasis. 80% presented with neurological symptoms, 76% with metachronous tumours. The median age was 60 years (39–84). 70% of lesions were less than 2cm in maximum diameter; 20% received radiosurgery to the resection bed following surgery. The marginal tumour dose ranged from 14- 25 Gy (lower doses used post-resection). There were few documented side effects (seizure 8%, radionecrosis 4%). 70% had radiological response of stable disease or partial response on MRI 6 weeks post treatment (follow-up thereafter was clinical). With a median follow up of 36 months, the median overall survival (OS) of patients with SRS was 8.5 months (1–43); 9 patients remain alive 20–39 months post-treatment. Previously collected data for the centre’s WBRT shows median survival of 2.92 months (2.22–3.63), 174 patients treated in 2012, median age 60 (24–86). Delivered dose was 20Gy in 5 fractions (20/5) in 85% (other regimens included 30/10, 20/4, 12/2). Common primary sites in both groups were Lung, Renal, Colorectal & Breast. CONCLUSION: SRS provides a low morbidity, effective palliative approach for selected patients with oligometastatic brain disease. The difference in OS between the groups suggests our selection methods are robust, though the observed range in the SRS group of 1–43 months demonstrates the uncertainties in outcome in intracerebral metastatic disease

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